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A ring resonator involves a scattering process where a part of the output is fed again into the input. The same formal structure is encountered in the problem of time travel in a neighborhood of a closed timelike curve (CTC). We know how to…

Quantum Physics · Physics 2022-07-19 Marek Czachor

Closed timelike curves are striking predictions of general relativity allowing for time-travel. They are afflicted by notorious causality issues (e.g. grandfather's paradox). Quantum models where a qubit travels back in time solve these…

The possible existence of closed timelike curves (CTCs) draws attention to fundamental questions about what is physically possible and what is not. An example is the "no cloning theorem" in quantum mechanics, which states that no physical…

Quantum Physics · Physics 2015-06-05 D. Ahn , C. R. Myers , T. C. Ralph , R. B. Mann

Inspired by some recent works of Tippett-Tsang and Mallary-Khanna-Price, we present a new spacetime model containing closed timelike curves (CTCs). This model is obtained postulating an ad hoc Lorentzian metric on $\mathbb{R}^4$, which…

General Relativity and Quantum Cosmology · Physics 2018-09-07 Davide Fermi , Livio Pizzocchero

The existence of time machines, understood as spacetime constructions exhibiting physically realised closed timelike curves (CTCs), would raise fundamental problems with causality and challenge our current understanding of classical and…

General Relativity and Quantum Cosmology · Physics 2009-11-07 G. M. Shore

We present a cyclic symmetric space-time, admitting closed time-like curves (CTCs) which appear after a certain instant of time, i. e., a time-machine space-time. These closed time-like curves evolve from an initial spacelike hypersurface…

General Relativity and Quantum Cosmology · Physics 2021-05-19 Faizuddin Ahmed

We study the power of closed timelike curves (CTCs) and other nonlinear extensions of quantum mechanics for distinguishing nonorthogonal states and speeding up hard computations. If a CTC-assisted computer is presented with a labeled…

Quantum Physics · Physics 2009-10-29 Charles H. Bennett , Debbie Leung , Graeme Smith , John A. Smolin

We analyze how the presence of closed timelike curves (CTCs) characterizing a time machine can be discerned by placing a local particle detector in a region of spacetime which is causally disconnected from the CTCs. Our study shows that not…

Quantum Physics · Physics 2024-07-19 Ana Alonso-Serrano , Erickson Tjoa , Luis J. Garay , Eduardo Martín-Martínez

For time travel to be consistent with the known laws of physics, the resulting paradoxes must be resolved. It has been suggested that parallel timelines (a.k.a. multiple histories) may provide a resolution. However, so far, a concrete…

Quantum Physics · Physics 2024-04-30 Barak Shoshany , Zipora Stober

We consider the motion of a gyroscope on a closed timelike curve (CTC). A gyroscope is identified with a unit-length spacelike vector - a spin-vector - orthogonal to the tangent to the CTC, and satisfying the equations of Fermi-Walker…

General Relativity and Quantum Cosmology · Physics 2026-01-23 Brien C. Nolan

General relativity allows solutions exhibiting closed timelike curves. Time travel generates paradoxes and quantum mechanics generalizations were proposed to solve those paradoxes. The implications of self-consistent interactions on acausal…

General Physics · Physics 2009-01-05 Florin Moldoveanu

We study the nature of entanglement in presence of Deutschian closed timelike curves (D-CTCs) and we observe that qubits traveling along a D-CTC allow unambiguous discrimination of Bell states with Local Operations and Classical…

Quantum Physics · Physics 2022-10-20 Subhayan Roy Moulick , Prasanta K. Panigrahi

The spacetime metric around a rotating SuperConductive Ring (SCR) is deduced from the gravitomagnetic London moment in rotating superconductors. It is shown that theoretically it is possible to generate Closed Timelike Curves (CTC) with…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Clovis Jacinto de Matos

In a recent paper, Mallett found a solution of the Einstein equations in which closed timelike curves (CTC's) are present in the empty space outside an infinitely long cylinder of light moving in circular paths around an axis. Here we show…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ken D. Olum , Allen Everett

Recently Burrage, de Rham, Heisenberg and Tolley have constructed eternal, classical solutions with closed timelike curves (CTCs) in a Galileon model coupled to an auxiliary scalar field. These theories contain at least two distinct metrics…

High Energy Physics - Theory · Physics 2012-11-20 Jarah Evslin

Interacting quantum fields on spacetimes containing regions of closed timelike curves (CTCs) are subject to a non-unitary evolution $X$. Recently, a prescription has been proposed, which restores unitarity of the evolution by modifying the…

High Energy Physics - Theory · Physics 2008-11-26 C. J. Fewster , C. G. Wells

According to the set theory, we prove that objects moving along closed timelike curves (CTCs) should belong to proper classes, but never to any set. Particles in a set have to change own some properties when they come into a CVC in order to…

General Physics · Physics 2012-07-16 Zhongzhu Liu

We present a modification to a 'rotating' version of the dynamical Alcubierre spacetime, which was previously shown to permit closed timelike curves. We find that if the effective rotation rate is made dependent on the spacetime coordinates…

General Relativity and Quantum Cosmology · Physics 2025-03-26 Achintya Sajeendran , Timothy C. Ralph

Modifying the discrete mechanics proposed by T.D. Lee, we construct a class of discrete classical Hamiltonian systems, in which time is one of the dynamical variables. This includes a toy model of time machines which can travel forward and…

Quantum Physics · Physics 2013-10-11 Hans-Thomas Elze

In a recent Letter, Bennett and coworkers [1] argue that proofs of exotic quantum effects using closed timelike curves (CTC's) based on the work of Deutsch [2], or other nonlinear quantum dynamics, suffer from a fallacy that they call the…

Quantum Physics · Physics 2010-06-10 Eric G. Cavalcanti , Nicolas C. Menicucci